Hi guys, I'm a bit shocked and surprised to see that after more than 2 weeks there are no Storm Call guides out, only EK, EK and EK. This makes me sad, because Storm Call has more or less the same clear speed as EK (even faster if done right).

With the new support gem, Spell Cascade, Storm Call gets even more viable for both bosses and clearing maps. The build can be both budget and expensive, depending on how far you want to push it. I did 36 challenges with my Storm Call Inquisitor.

!!! 3.4 UPDATED!!!

3.4 UPDATE: [/b]

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Ok guys, I did some skill trees. They're all mind over matter based.

Inquisitor is still the strongest , but the other classes give good other benefits, elementalist gives us free life leech (bereks grip can be dropped), trickster is extremely tanky and scion/assassin are viable options too, but i would recommend the other three classes. If you plan this build as league starter, I recommend you to use warlords mark + blasphemy instead of herald of thunder and skip wrath until you have essence worm.
Here are the PoB links (all with MoM):

Inquisitor:

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https://pastebin.com/fp9FTDZe

Trickster

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https://pastebin.com/zYcF1TzU

Elementalist

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https://pastebin.com/AGXcwhQv

Assassin

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https://pastebin.com/HrMBkskV

Scion (inquisitor+elementalist)

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https://pastebin.com/nmyfaikJ

IF you want acro, drop some damage nodes or the left side of the tree. up to you
If you got questions, feedback or even your own custom skill tree, just write here and I'll reply asap ;)

We gotta do some maths, since PoB can't calculate the dps:
If Storm Call overlaps (Spell Cascade), the average hit is multiplied by 2 and in the end, we multiply the damage by the Cast Rate.
DPS with overlaps: ~1128215
DPS without overlaps: ~564107
So with perfect gear and jewels 1.5 million should be possible

-not the fastest guardian/shaper killer (other bosses are fine) of course
-lag/fps drops because Storm Call is badly programmed (dynamic resolution MAY help)
-needs positioning sometimes and is not a facetanking build
-getting endgame jewels are expensive, especially with 2x critmulti and life

Rest can be varied. I use Immortal Call + Warlords mark, but it's up to your choice. And a lvl 1 clarity is used because of watchers eye, but can be dropped.

Detailed explanation:

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Those three uniques are mandatory:

Inpulsa's gives us damage, shock effect (important vs bosses) and the explosions (insane clear). Also offers life which is quite nice. Essence Worm is for Wrath, so I still can run Herald of Thunder and Ice. Kaom's roots are great for this build, since you're shieldcharging anyways, movement speed doesn't matter much. Stun/freeze immunity, high life and the cheap price make them quite good. For Enchants: Use the faster attacks/casts when killed recently for mapping, for guardians/shaper use "adds lightning damage when you haven't killed recently".
Berek's grip

is the most expensive unique, but only needed for endgame. Until you can afford Watcher's eye

with Mana leech (2nd affix doesn't matter much, I chose clarity+mana recovery out of convenience) AND Berek's grip, run Blasphemy+Warlord's mark instead of HoI and HoT. Mana leech is important! Rest of the gear is Rare, should focus on life and resistances. On the Amulet Crit multi and cast speed are helpful. I highly recommend getting the "reduced Storm Call Duration" enchant on the helmet, it helps a lot clearing the content. For jewels always try to get at least one Critmulti affix and life, ideal would be 2x Critmulti affixes. Shield and Dagger/Sceptre need Spell Crit Chance, %spell damage or %lightning damage and if possible, attack and cast speed. Flat lightning damage to spells is also very nice.

Important details(!):

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As previously mentioned, to get full of the Spell Cascade damage, you need to overlap 2 circles. Thats why you aim with your mouse cursor in front or behind the monster, especially when fighting bosses. Keep that in mind!

Alternative Gear choices/Build Variants

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Carcass Jack (Inpulsa is better though)
Choir of the Storm

Templar with MoM instead of Acro (less damage, more survivability, you need to drop HoI.)
Trickster/Assassin
Elementalist
Scion
Berserker
For all non-inquisitor builds you need to swap in lightning penetration gem.

Leveling

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Storm Call can get used at level 12, spell cascade at 4, but I recommend you to start with freezing pulse or some other basic spell, since storm call without the less duration gem is kinda slow, but at level 31 and onwards its fun to play.
Travel straight to the witch nodes and shadow nodes, get MoM while leveling and unspec it later. You can use 1-2 heralds, depending on your mana issues. Get warlord's mark and blasphemy at level 31, the you can drop both heralds, keep going with MoM for now until you reach level 70. When reaching level 70 you can decide to keep MoM and travel the right side of the tree later (acro/spell acro etc.) and go for damage nodes, otherwise unspec MoM, get Acro and the rest of the Nodes. The build is quite complete at level 93, so the last 7 points are only worth if you really want to squeeze every last drop of dps.

Q: Do I need the reduced Storm Call duration enchant?
A: Well, it's not a dps buff, but more a quality of life buff. You hit sooner, leech sooner, but it's not game breaking ;).

Q: Do I need to use a dagger?
A: No, not necessarily. A good rolled Sceptre is even stronger in many cases and can have a cast speed roll.

Q: Itemfilter in the videos?
A: Neversinks very-strict.

Q: Does the skill lag a lot?
A: I can't 100% tell since it depends on your pc. But setting up dynamic resolution may help. Better try it for yourself. The MTX doesn't help with the fps unfortunately.

Q: Does a 5l Inpulsa's work?
A: Yes, but single target suffers quite a bit.

Q: Why no vinktar's?
A: Storm Call has only 80% effectiveness, so the added damage from vinktars is quite weak, atziris promise is much better. Also 1 sip vs 2 sips, which is a huge difference in boss fights.

What's the highest tier map you have completed with this? How does it far against end game bosses and reflect maps?

As the title says, I did all content with it, including Tier 16/17 (Guardians + Shaper). Tier 15 bosses are dead under 5 seconds (unless it's a boss with phases like the T15 Brine King) so it is a very viable build. Guardians/Shaper take a little longer, because you can't really nuke them down due to the very high HP pool, but it's still comfortable.

Map reflect mod is a no-go, but rare elemental reflect ('thorns') mobs are no problem.
I will upload some videos later, showing general mapping and boss fights.

I am 99% sure that the effect of spell echo is shown in POB. With it not checked the cast rate is only 3.78. Apart from that great guide. Also i found when i was lacking currency for a 6link inpulsa's an elder or shaper helm can make for a rather cheap pseudo 6 link. You can get inc aoe, hypothermia (if you have enough cold dmg or a call of the brotherhood) and socketed spells have extra crit chance in a shaper helm or conc effect and less duration in an elder helm.